Replaced stock rear tire on my Gary Fisher bike. The rear traction the Weirwolf provides is incredible. I don't loose traction on climbs unless there is lots of loose gravel etc. Much more efficient climbs. Also replaced the front tire with a Panaracer Rampage. The combination has increased my confidence in corners. I am riding faster and more aggressive as a result of the upgrade. Highly recommend! Should be one of your first upgrades.